Prediction of recrystallization times in electroplated copper thin films

Room temperature recrystallization responses of blanket electroplated Cu thin films deposited under various conditions were monitored in real-time using synchrotron X-ray diffraction. Nominal control of electroplating parameters such as plating current, bath chemistry, and plating time was found to be insufficient to ensure repeatability of the 50% recrystallization time, τ50, from sample to sample even though the thickness variations between samples were insignificant. Real-time X-ray analysis of samples from numerous electroplating baths showed that, for a given seed deposition process, a reliable estimation of τ50 at room temperature can be obtained from the ratio of the integrated intensities of the 111 and 200 Cu reflections, I−111/I−200, of the electroplated film at time zero (immediately after plating). Among the plating parameters investigated seed-layer texture most influenced this ratio and, hence, the subsequent room temperature recrystallization behavior of the plated film.